1. Field of the Invention
The present invention relates to an optical plate for use in, for example, a backlight module, the backlight module typically being employed in a liquid crystal display (LCD).
2. Discussion of the Related Art
The weight and/or the thinness of LCD panels makes them suitable for use in a wide variety of electronic devices such as personal digital assistants (PDAs), mobile phones, portable personal computers, and other electronic appliances. Liquid crystal is a substance that does not emit light. Instead, the liquid crystal relies on light from a light source to display images. In the case of a LCD panel, the light source is a backlight module.
FIG. 8 is an exploded, lateral cross-sectional view of a typical direct type backlight module 10 employing a typical optical diffusion plate 13. The backlight module 10 includes a housing 11, a plurality of lamps 12 disposed on a base of the housing 11, the light diffusion plate 13, and a prism sheet 15 stacked on a top of the housing 11, respectively. The housing 11 is configured for concentrating the direct and reflected light, of the lamps 12, towards the prism sheet 15. The light diffusion plate 13 includes a plurality of dispersion particles 131. The dispersion particles 131 are configured for scattering the light, and thereby enhancing the uniformity of light exiting the light diffusion plate 13. The front of the prism sheet 15 includes a plurality of V-shaped structures. The V-shaped structures are configured for collimating, to a certain extent, the received light.
In use, light from the lamps 12 enters the prism sheet 15 after being scattered in the light diffusion plate 13. The light are refracted in the prism sheet 15 and collimated by the V-shaped structures, to increase the brightness, and finally onto an LCD panel (not shown) disposed above the prism sheet 15. Although the brightness may be improved by the V-shaped structures, the viewing angle may be narrowed. In addition, because of the manufacturing methodology, a plurality of air pockets are formed between the light diffusion plate 13 and the prism sheet 15. Thus when the backlight module 10 is in use, light passing through the air pockets undergoes total reflection at the air pockets and as a result the brightness is reduced.
Therefore, a new optical means is desired in order to overcome the above-described shortcomings.